1. Technical Field
This invention relates to rolling mills in general and more particularly to rolling mills where steel is being reduced to thin gauge sheets and strips and still more particularly to coolant applying devices for said rolling mills.
2. Description of the Prior Art
Prior coolant applying devices used on rolling mills have arranged elongated manifolds parallel with the work and backup rolls of the rolling mill and directed fluids, such as water, through individual spray nozzles on the manifolds against the rolls of the mill to provide termperature control and lubrication during an actual rolling operation.
Several prior art patents relate to pilot operated control valves including U.S. Pat. Nos. 3,145,967, 3,159,374, and 4,391,296. In each of these patents solenoid operated valves are disclosed with theoretically control fluid directed therethrough. In U.S. Pat. No. 3,145,967 an elastic sleeve is arranged in spaced relation about a core positioned in a fluid passageway to be controlled. An annular cavity in the valve around the exterior surface of the elastic sleeve enables air pressure to be introduced so as to distort the plastic sleeve inwardly against the core and thus close the fluid passageway. The air pressure is controlled by a solenoid operated valve.
In U.S. Pat. No. 3,159,374 a flexible diaphragm is positioned to intercept a fluid passageway through the valve when fluid pressure is applied to one side of the diaphragm so as to distort the same into closing relation to the fluid passageway controlled thereby. The fluid pressure for operating the diaphragm is controlled by a solenoid valve.
U.S. Pat. No. 4,391,296 discloses a valve in which a valve plug moves into and out of closing relation with respect to a fluid passageway extending between an inlet port and an outlet port with the valve plug being urged to closed position in the fluid passageway by a spring and moved to open position by a solenoid. A piston is positioned in an extension of the fluid passageway and a secondary inlet port is in communication with the fluid passageway below the piston so that manual operation of the valve can be achieved by introducing hydraulic pressure into the second inlet port so as to move the piston in the fluid passageway where it will engage and open the valve plug.
Applicant's U.S. Pat. No. 4,568,026 discloses as assembly of pilot operated coolant control valves in which the individual valves are arranged in cartridges and in which solenoid actuated pilot valves must remain energized to afford continuous coolant flow. The control valves of the present invention are dependent upon fluid pressure of the coolant supply in the manifold assembly. These valves must remain open despite any power failure that occurs and continue spraying the coolant liquid as long as the rolling mill is operating to protect the rolls against distortion and such other damage as will occur if the coolant is discontinued. The prior art pilot operated control valves are unable to maintain a fail-safe open condition upon a failure of the solenoid actuating circuits or faulty operation due to dirt or particles of foreign materials in the coolant supply. Generally the prior art coolant valves require complete dismantling of the valve bodies and the operable parts whereas in the present invention the valve bodies defining the valve seats and the movable valve elements take the form of quickly and easily removable cartridges and due to their novel construction and operating patterns are able to operate successsfully and remain open while the rolling mill is operating despite any failure in the pilot valves or their control medium.
This invention eliminates many of the problems that heretofore existed in connection with pilot operated coolant control valves arranged in and supplied by manifold assemblies.